European Patent Application EP-A-O 033 094 describes imidazo[1,2-a]pyridines which have in position 8 an aryl substituent which is preferably a phenyl, thienyl or pyridyl radical or a phenyl radical which is substituted by chlorine, fluorine, methyl, tert.-butyl, trifluoromethyl, methoxy or cyano. Aryl radicals mentioned as particularly interesting in EP-A-0 033 094 are the radicals phenyl, o- or p-fluorophenyl, p-chlorophenyl and 2,4,6-trimethylphenyl, of which the radicals phenyl, o- or p-fluorophenyl and 2,4,6-trimethylphenyl are particularly preferred. European Patent Applications EP-A-0 204 285, EP-A-0 228 006, EP-A-0 268 989 and EP-A-0 308 917 describe imidazo[1,2-a]pyridines which have in position 3 an unsaturated aliphatic radical, in particular a (substituted) alkynyl radical. European Patent Application EP-A-0 266 890 describes imidazo[1,2-a]pyridines which are substituted in position 8 by an alkenyl, alkyl or cycloalkylalkyl radical.